1. Field of the Invention
The present invention relates to an array antenna transceiver, and more particularly to an array antenna transceiver in which transmission and reception can be continued even when a reference signal supply system is failed.
2. Description of the Related Art
An array antenna transceiver has a transceiver section provided for every antenna element and a transceiver section control circuit which controls them. In case of reception, the array antenna transceiver carries out a process for frequency conversion to a signal received by each antenna element in the transceiver section and sends to the transceiver section control circuit, which carries out a weighting operation and a synthesizing operation. In case of transmission, a signal is subjected to a weighting operation in the transceiver section control circuit and is sent to the transceiver section, which carries out a transmission process for frequency conversion and transmits from each antenna element.
FIG. 1 is a block diagram of a conventional array antenna transceiver. Referring to FIG. 1, the conventional array antenna transceiver is composed of an antenna section 201, N transceiver sections 202-1 to 202-N, N reference signals 203-1 to 203-N, a transceiver section control circuit 204, a hybrid 205, and a common reference signal generating section 206. Generally, the transceiver sections are provided for inputs and outputs of the antenna sections, and the N transceiver sections are provided in this conventional example. To supply a reference signal, a synchronization signal is supplied to the common reference signal generating section 206, which generates a reference signal. The generated reference signal is distributed to the N transceiver sections 202-1 to 202-N by the hybrid 205. Through this method, the reference signal is generated by the common reference signal generating section 206 and supplied to all the transceiver sections. Therefore, the reference signals can be supplied to all the transceiver sections from a single signal source in common.
In the conventional array antenna transceiver shown in FIG. 1, the common reference signal generating section is provided outside of the respective transceiver sections as a reference signal source, and the output thereof is distributed to the respective transceiver sections. Thus, synchronization between the transceiver sections can be established. The reason why the synchronization is established between the transceiver sections in this way is that the weighting operation and synthesizing operation to a transmission or reception signal cannot be carried out with high precision, unless the transceiver sections for the number of antenna elements are not synchronous with each other in the array antenna transceiver.
On the other hand, the method of generating a reference signal individually for every transceiver section without using the common reference signal generating section could be thought of. However, in such a case, there is possibility that the reference signals different in phase, amplitude and frequency are supplied to the respective transceiver sections. Therefore, to establish synchronization between the transceiver sections, calibration would have to be separately carried out.
For the above reason, in the conventional array antenna transceiver, the signal common to all the transceiver sections is supplied from the common reference signal generating section. In this way, it is possible to carry out the weighting operation and the synthesizing operation to the transmission and reception signals in the high precision without carrying out any calibration.
However, in the above-mentioned conventional array antenna transceiver, the signal transmission and reception cannot be carried out in all the transceiver blocks when the common reference signal generating section is set to a non-operating state because of a kind of trouble.
In conjunction with an array antenna forming method is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 5-191128). In this reference, a unit reception system is formed of unit receiving blocks 1-1 to 1-N, phase synchronizing blocks 2-1 to N-1 and phase reference block 3, and the unit receiving block is composed of a reception antenna 7 and a reception converter 8. A local signal frequency for the reception converter 8 is locked to a predetermined frequency based on the external reference signal. The external reference signal is supplied into the converter through an output terminal of the reception converter 8. By using the reference signal as a common reference signal to the respective reception converters 8, the local signal frequencies of the converters are made common without local distribution in a high frequency band. In this way, all the reception converters can be made operated in common even if the number of elements of an adaptive array antenna is many.
Also, an antenna apparatus is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 5-281326). In this reference, the antenna apparatus is composed of a first antenna row which is composed of at least two antennas which are arranged in a horizontal direction orthogonal to a radio wave arrival direction and a radio wave facing plane which is perpendicular to the radio wave arrival direction. A drive section drives the first antenna row to an azimuth direction. A phase difference detecting section detects the phase difference between the reception signals of the antennas of the first antenna row. A drive control section controls the drive section to drive the first antenna row by means in the direction in which the phase difference detected by the phase difference detecting section is zero. A second antenna row is composed of a plurality of antennas arranged in a vertical direction orthogonal to the horizontal direction in parallel to each other. A drive section drives the second antenna row in an azimuth direction. A drive control section controls to the drive section to drive the second antenna row into the substantially same direction as the directing direction of the first antenna row. A reference signal generation section generates a reference signal from the reception signal of at least one of the antennas in the first and second antenna rows. A signal control section generates a comparison signal from the reception signal of at least one of the other antennas and converts the frequency of the comparison signal such that the frequency of the comparison signal is coincident with that of the reference signal, and controls the phase of the comparison signal such that the phase of the comparison signal is coincident with the phase of the reference signal. A synthesizing section synthesizes the reference signal and the comparison signal controlled by the signal control section.
Also, an adaptive array antenna apparatus of an LMS (least mean square) system is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 7-154129). In this reference, the adaptive array antenna apparatus is composed of a plurality of antennas and multiplying sections. The multiplying sections multiply weighting coefficients individually to radio wave signals received by said a plurality of antennas, respectively. An adding section adds the respective output signals of the multiplying section to produce an output signal of the antenna apparatus. An extracting section extracts a pilot signal indicating predetermined contents from the output signal of the adding section. A reference signal generating section compensates the output signal of the adding section based on the pilot signal extracted by the extracting section to generate a reference signal. A subtracting section calculates a signal indicative of the difference between the output signal of the adding section and the reference signal. A control section controls each weighting coefficient of the multiplying section to minimize the difference signal. A pattern signal is subjected to time division Multiplexing with a data signal and contained for every predetermined interval in the radio wave signal. The extracting section extracts the pilot signal subjected to the time division multiplexing.
Also, a mobile terminal reception antenna system is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 8-172312). In this reference, an array antenna is composed of at least two antenna units. First frequency converters are provided for the antenna units and convert reception signals received by the antenna units into first intermediate frequency signals in frequency. A first common local oscillator supplies a first local oscillation signal to the first frequency converters in common. A plurality of second frequency converters convert the first intermediate frequency signals into second intermediate frequency signals, respectively. A synthesizing unit in-phase synthesizes the plurality of second intermediate frequency signals outputted from the plurality of second frequency converters to generate a reception signal. First and second mono-pulse circuits carry out frequency conversion to the first intermediate frequency signal outputted from two of the first frequency converters which correspond to the antenna units provided on the left side and the right of the antenna units. A phase detecting section detects the phase difference of the output of the first mono-pulse circuit and the output of the second mono-pulse circuit. A turning section turns the array antenna in the horizontal plane based on the output of the phase detecting section. A specific frequency converter as one of the plurality of second frequency converters outputs a reference signal. A second local PLL oscillator supplies a second local oscillation signal to the first and second mono-pulse circuits in common. A control section is provided for each of the plurality of second frequency converters other than the specific frequency converter to control such that a second intermediate frequency signal in phase to the reference signal is outputted. The turn section turns the antenna units for the azimuth of the array antenna to be coincident with the direction of the arrival of the radio wave.
Also, an array antenna apparatus is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 10-79619). In this reference, the array antenna apparatus is composed of a plurality of antenna elements and a reference signal generating unit. Weighting sections carry out complex weighting operations to the outputs of the antenna elements, respectively. A branching unit outputs the outputs of the antenna elements to the weighting section and weighting control section. A synthesizing section synthesizes the signals after the complex weighting operation. The antenna element outputs determined based on a delay time distribution of incoming wave are controlled.
An object of the present invention is to provide an array antenna transceiver in which transmission and reception can be carried out even if a common reference signal generating section has stopped operation due to a kind of trouble such as a failure, or a tranceiver block cannot detect the input of a reference signal from a common reference signal generating section.
In an aspect of the present invention, an array antenna transceiver includes an antenna section, N transceiver blocks, a common reference signal generating section and a transceiver control section. The antenna section has antenna elements. The N (N is an integer more than 1) transceiver blocks are connected to the antenna elements. Each of the N transceiver blocks generates an individual reference signal. The transceiver block carries out transmission of a transmission signal and reception of a reception signal based on an common reference signal using a corresponding antenna element as a part of an array antenna in an array mode and based on said individual reference signal using the corresponding antenna element as an individual antenna element in an individual mode. The common reference signal generating section supplies the common reference signal to the N transceiver blocks. The transceiver control section sets said array mode when said common reference signal is used, and said individual mode when said individual synchronization signal is used.
Each of the N transceiver blocks may include an individual reference signal generating section which generates the individual reference signal.
Also, each of the N transceiver blocks may include a transceiver section, a switch, and a switching control circuit. The transceiver section carries out the transmission of the transmission signal and the reception of the reception signal using the corresponding antenna element as the part of the array antenna in the array mode based on the common reference signal and using the corresponding antenna element as the individual antenna element in the individual mode based on the individual reference signal. The switching control circuit controls the switch to supply the common reference signal to the transceiver section, when the common reference signal is supplied to the transceiver block. Also, the switching control circuit controls the switch to supply the individual reference signal to the transceiver section, when the common reference signal is not supplied to the transceiver block.
In this case, each of the N transceiver blocks may include a detecting circuit which determines whether the common reference signal is supplied to the transceiver block.
Also, the switching control circuit may control the switch to supply the common reference signal to the transceiver section, when the common reference signal is supplied to the transceiver block. Also, the switching control circuit may control the switch to supply the individual reference signal to the transceiver section, when the common reference signal is not supplied to the transceiver block or when the common reference signal generating section is not in an operation state.
Also, the array antenna transceiver may further include an alarm detecting circuit which determines whether or not the common reference signal generating section is in the operation state.
In another aspect of the present invention, a method of ensuring continuity of transmission and reception in an array antenna transceiver, is attained by (a) generating a common reference signal normally by a common reference signal generating circuit; by (b) generating an individual reference signal; by (c) setting each of N transceiver blocks connected to antenna elements to one of an array mode and an individual mode based on whether the common reference signal is available; by (d) carrying out one of an array mode process and an individual mode process to a transmission signal and a reception signal to and from each of the N transceiver blocks based on whether the transceiver block is set to the array mode or the individual mode; and by (e) carrying out transmission of the transmission signal and reception of the reception signal using the corresponding antenna element as a part of an array antenna in the array mode and using the corresponding antenna element as an individual antenna element in the individual mode.
In the (c) setting step, each of N transceiver blocks may be set to the array mode when the common reference signal is available, and to the individual mode when the common reference signal is not available.
Also, the (e) carrying out step may be attained by validating the common reference signal and invalidating the individual reference signal, in the array mode; and by validating the individual reference signal and invalidating the common reference signal, in the individual mode.
Also, in the (c) setting step, it may be determined whether the common reference signal is supplied to each of the N transceiver blocks, and then it may be determined for each of the N transceiver blocks that the common reference signal is available, when it is determined that the common reference signal is supplied to the N transceiver block.
In addition, the (c) setting step may further include the steps of: determining whether or not the common reference signal generating section is in an operation state; and determining for each of the N transceiver blocks that the common reference signal is available, when it is determined that the common reference signal generating section is in an operation state.